Abstract: To provide a novel polymer capable of reducing sublimate during film formation and a composition comprising the same. The polymer (A) according to the present invention comprises at least one structural unit selected from the group consisting of Unit (a), Unit (b), Unit (c) and Unit (d) having certain structures, wherein, na, nb, nc and nd, which are the numbers of repetition respectively of Units (a), (b), (c) and (d), satisfy the following formulae: na+nb>0, nc?0 and nd?0.